TcpReceive

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 Function Block - Receives characters over a socket connection.

Inputs

Input

Data Type

Range

Unit

Default

Description

Execute

BOOL

0 to 1

N/A

No default

On the rising edge, receive a string over a socket connection.

ID

UDINT

N/A

N/A

No default

The ID of the client socket.

MaxChar

STRING

N/A

User units

No default

The number of characters to receive.

Outputs

Output

Data Type

Range

Unit

Description

Done

BOOL

 

 

If TRUE, the command completed successfully.

Error

BOOL

 

 

If TRUE, an error has occurred.

ErrorID

DINT

 

 

Indicates the error if Error output is TRUE.

See the table in File and TCP/IP Function Block ErrorIDs.

Data

STRING

 

 

String of received characters.

Remarks


  • It is possible that the socket becomes invalid if an error occurs in the TCP connection after this function block is called.
    Use the TcpIsValid function block after TcpSend.
    If the socket is no longer valid, close it using the TcpClose function block.
  • It is possible that the number of characters actually received is less than the number expected.
    • In this case, call this function again on the next cycle to receive the pending characters.

Figure 1: TcpReceive

FBD Language Example

Not available.

FFLD Language Example

Not available.

IL Language Example

Not available.

ST Language Example

(* TcpReceive example *)
CASE StepCounter OF
0:
  Inst_TcpReceive(TRUE, MySocketID, 128);
  StepCounter := StepCounter + 1;
1:
  Inst_TcpReceive(TRUE, MySocketID, 128);
  IF Inst_TcpReceive.Done THEN
     ReceivedData := Inst_TcpReceive.Data;
     Inst_TcpReceive(FALSE, 0, 0);
     StepCounter := StepCounter + 1;
  END_IF;
END_CASE;

See Also